The main goal of this proposal is to develop a novel technology to screen newborns for serious Primary Immune Deficiencies (PIDs), including quantitative deficiencies of T cells (e.g., SCID) and B cells (e.g., XLA). Diagnosis of these deficiencies in the newborn period could save lives and reduce societal costs. In pilot work we have developed a microfluidic channel system that enables specific capture and labeling of immune cells from a single drop of blood. We have also developed a glass-embedded waveguide sensor that can quantitate cells lying in the evanescent field of the waveguide core. These technologies are distinctive in that they allow for both a very low per-test cost as well as a very low equipment cost, thus enabling point-of-care testing in the newborn nursery. It also will enable testing without the need for specialized training, dedicated technicians, expensive reagents, or handling of dried blood spots. Our goals in this application are to bring together these two technologies and to establish that the resulting device can quantitate cells from infant blood, thus validating this novel approach for diagnosing PIDs in the neonatal period. Our Aims are to: 1. Integrate the Waveguides and Microfluidics to Capture and Quantitate Cells from Human Blood. We will fabricate waveguides and microfluidic channels using the Stanford Nanofabrication Facility and the Stanford Microfluidics Foundry. These technologies will be integrated and the resulting detector will be tested and calibrated using blood cells from adult human blood. 2. Establish the Utility of Protein Tyrosine Kinase 7 (PTK7) for Quantitation of Neonatal T Cells. Because maternal engraftment of T cell precursors can foil traditional approaches to diagnosing SCID, we will utilize the newly discovered marker of neonatal T cells PTK7 to capture and enumerate T cells from newborn heel stick blood. 3. Quantitate B cells in Neonatal Blood and Integrate to Simultaneously Count T Cells and B Cells. We will test a variety of B-cell-specific markers for their capability to capture and detect human B cells in our microfluidic channels. We will then count B cells from infant heel stick blood. Finally we will bring together B cell and T cell detection into a single diagnostic test. PUBLIC HEALTH RELEVANCE: Primary immunodeficiencies (PIDs) affect 1 in 1,200 people in the US. If serious PIDs could be diagnosed in newborns, early treatment would save lives and reduce societal costs. These studies will enable development of a novel detector technology that can screen newborns for T cell and B cell deficiencies rapidly and at very low cost.